Fall Pipe End Positioning With Independent Survey Rotation
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Solution Overview
Problem
Prior art fall pipe ROVs experience reduced accuracy and increased fuel consumption due to misalignment between the vessel and the ROV, requiring thruster-assisted rotation for orientation, which affects rock installation precision and productivity.
Innovation Solution
A submersible frame with integrated propulsion and survey equipment, featuring a rotation system that uses an actuator to independently rotate the survey equipment about a vertical axis, eliminating the need for thruster-assisted rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the vessel is positioned head seas to maintain correct orientation, then the orientation of survey equipment is maintained, but the thrust available for positioning is reduced, leading to decreased positioning accuracy
Solution Approach 1:
The system is divided into two independent rotational components: the submersible frame and the survey equipment. The survey equipment can rotate independently about the vertical axis relative to the submersible frame, allowing the frame to maintain positioning thrust while the survey equipment achieves correct orientation independently.
Solution Approach 2:
The actuator system provides multi-functionality by enabling independent rotation of survey equipment while the propulsion system maintains positioning. This allows the same system to simultaneously achieve positioning accuracy and orientation correctness without compromising either function.
2Measurement precision
If thrusters are used to rotate the ROV for correct orientation, then the orientation of inspection arms is achieved, but power consumption increases and positioning accuracy decreases
Solution Approach 1:
The rotational function is segmented from the propulsion system. A dedicated actuator mechanism handles rotation of survey equipment independently, while thrusters focus solely on positioning. This separation eliminates the need for high-power thruster operation during orientation adjustments.
Solution Approach 2:
The mechanical rotation system (actuator with rack and pinion) replaces the thruster-based rotation method. This substitution uses a specialized mechanical mechanism designed for rotation rather than using propulsion thrusters for dual purposes, reducing overall power consumption.
3Manufacturing precision
If the vessel moves parallel to the dumping trajectory, then the rock installation precision is improved, but the fuel consumption increases due to vessel misalignment
Solution Approach 1:
The system separates vessel navigation from survey equipment orientation. The vessel can maintain optimal head seas positioning for fuel efficiency while the survey equipment independently orients to achieve precise rock dumping trajectory alignment.
Solution Approach 2:
The independent survey equipment rotation system acts as an intermediary between the vessel's navigation position and the required dumping trajectory. It mediates the orientation requirement without forcing the vessel into suboptimal navigation positions.
4Ease of operation
If the ROV rotates about its own axis using thrusters, then the correct orientation of supporting arms is achieved, but the thrust available for positioning is reduced
Solution Approach 1:
The rotational capability is segmented into a dedicated actuator mechanism independent of the propulsion system. This allows the survey equipment to achieve correct orientation while the thrusters maintain full thrust availability for positioning operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances rock installation precision and productivity by maintaining thrust for positioning, reducing power consumption, and allowing accurate orientation of survey equipment even in misaligned conditions.
Implementation Method 1
the actuator being adapted to convert an energy input into a rotation of the second element when holding the first element, the rotation being about a vertical axis
Implementation Method 2
propulsion equipment adapted for moving the submersible frame in a horizontal plane, thereby controlling the position of the submersible frame independently from the vessel
Data Source
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AI summary
An arrangement for positioning a fall pipe end (414) during subsea rock installation, comprising: - a submersible frame (400) adapted to be lowered towards an underwater structure, comprising: - a first (401) frame structure carrying propulsion equipment (415) and a second frame structure (402) carrying survey equipment (406, 407); - a channel structure (410); - a rotation system comprising an actuator (403), the actuator (403) comprising a first (411) and a second element (412) and being adapted to convert an energy input into a rotation of the second element (412) when holding the first element (411); wherein the second element (412) is connected to the second frame structure (402), such that in suspended condition of the submersible frame (400), the survey equipment (406, 407) can be rotated about a vertical axis (409) by energizing the actuator (403), without using the propulsion equipment (415).